package com.example.question.dp.dp2;

public class Code01_70 {

    public int climbStairs(int n) {
        int[] dp = new int[n + 1];
        dp[0] = 1;
        dp[1] = 1;
        for (int i = 2; i < n + 1; i++) {
            dp[i] = dp[i - 1] + dp[i - 2];
        }
        return dp[n];
    }

    public int climbStairs2(int n) {
//        int[] dp = new int[n + 1];
//        dp[0] = 1;
//        dp[1] = 1;
        int pre = 1;
        int cur = 1;
        int next;
        for (int i = 2; i < n + 1; i++) {
//            dp[i] = dp[i - 1] + dp[i - 2];
            next = pre + cur;
            pre = cur;
            cur = next;
        }
        return cur;
    }
}
